JPS61260474A - Optical disk drive device - Google Patents

Abstract

PURPOSE:To secure a tracing control by outputting a digital signal corresponding to the frequency of the photoelectric conversion signal of the photodetector of an optical head from a frequency response counting means and converting it into an analog signal by a function digital/analog conversion means. CONSTITUTION:According to a speed detecting signal and a count value showing the position of a light spot on an optical disk 101, which is detected by a track crossing number counter 1 and a speed detecting circuit 2 at the time of accessing a track, a linear actuator drive control circuit 117 operates the optical head 104, and controls a relative speed with respect to the optical disk 101 of the light spot on the optical disk 101. The speed detecting circuit 2 detects the track of the optical disk 101 and the light spot, drives a linear actuator 116 so as to cancel the track fluctuation, and controls the relative speed between the track of the optical disk 101 and the light spot. Thus the constitution of an optical disk drive device can be simplified, and the track control can be stabilized.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a source disk drive device, and particularly to a source disk drive device that performs precise access control to allow a source spot to access any track on the source disk. be.

[Conventional technology]

Figure 6 shows, for example, the 1981 IEICE General National Conference 1.
This is a block diagram of an access control system published under the title ``2) Track access method for 0r source disks.'' In the figure, 101 is a block diagram of an access control system in which recording tracks with high-density pit rows are arranged concentrically or spirally in a large number of track grooves. A large number of original disks; 102 is a disk motor that rotates the original disk 101 mounted on a spindle; 103 is a disk motor 1;
A disk motor drive control circuit 104 for driving and controlling the rotation of 02 is formed on the original spot t-original disk 101,
This is an optical head that moves in the radial direction of the original disk. 1
05 is a frame body, 106 is a light source such as a semiconductor laser, 10
7tf: y remeter lens, 108Fi polarizing beam splitter, 109 is a λ/4 plate.

1) 0 is a mirror for changing the optical path; 1) 1 is an objective lens that focuses the original beam from the light source 106 onto the original disk 101 to form an original spot; 1) 2 is a mirror that converts the original spot into a recording track of the original disk 101. Objective lens 1) A tracking actuator that moves the objective lens 1 minutely in the radial direction of the original disk 101 in order to accurately position the objective lens 1) A tracking actuator that moves the objective lens 1 minutely in the radial direction of the original disk 101. 1) 2 divided beams that are reflected by the original disk 101 and return nine times to detect the source. It is a detector. It is composed of an optical head 104ti and the above-mentioned frame 105 to division source detector 1) 3.

1) 4 is a well-known addition/subtraction function that sums the outputs of divided photodetectors 1) 3 and outputs a sum signal that becomes an information signal, or subtracts the outputs of divided detectors 1) 3 to output a tracking error signal. Amplifier circuit 1) 5 is an addition/subtraction amplifier circuit 1) Tracking actuator 1) according to the tracking error signal of 4
Trunking actuator drive control circuit that drives 2, 1) 6#i original head 104t-original disk 1010
A linear actuator that moves in the radial direction, 1) T is a linear actuator drive control circuit that drives and controls the linear actuator 1) 6, 1) 8 is an addition/subtraction amplifier circuit 1)
1) A track crossing detection circuit which inputs the output of 4 and detects the number of 9 tracks traversed by the optical head 104; 1) 1 is a speed detector which detects the speed of the optical head 104; 120 is a speed detector 1) the output of 9; 12) is an acceleration detector that detects the acceleration of the optical head 104 by inputting a waveform storage circuit;
22 is μ as a microprocessor interface.
-〇PtJ interface. Although the tracking error signal is obtained by, for example, the well-known push-pull method, it may be obtained by the DPD method.

Next, the operation will be explained. First, the disk motor 102, that is, the original disk 101, starts rotating by the disk motor drive control circuit 103, and after reaching a steady rotation speed,
The tracking actuator drive control circuit 1) 5 operates based on the tracking error signal detected by the photodetector 1) 3 and the addition/subtraction amplifier circuit 1) 4 by the well-known operation of the optical head 104.
) 2 is driven, and the original beam spot follows the center of the track on the original disk 101 by moving the objective lens 1) 1. Furthermore, at this time, the tracking actuator drive control circuit 1) 5 also sends a tracking actuator drive signal to the linear actuator drive control circuit 1) 7, and the linear actuator drive control circuit 1) 7 drives the linear actuator 1) 6 at a low frequency. and optical head 1
04 is moved in the radial direction of the original disk 101 to reduce the movement of the tracking actuator 1)2.

In addition, at the time of track access, the number of tracks on the original disk 101 crossed by the one-source spot is counted by the track crossing detection circuit 1) 8, and at the same time, the moving speed of the optical head 104 detected by the speed detector 1) 9 is counted. Input IJ near actuator drive control circuit 1)
7, speed control is performed so that as the source spot approaches the target track, its speed approaches zero.

Furthermore, while the optical head 104 is moving, the speed detector 1) 9
From the moving speed of the optical head 104 detected by
The acceleration of the optical head 104 is detected by the acceleration detection circuit 120, and this detection signal is applied to the tracking actuator 1) 2 via the tracking actuator drive control circuit 1) 5, thereby controlling the tracking actuator 1) when the optical head 104 accelerates or decelerates. The inertial force of the objective lens 1) 1 applied to the tracking actuator 1) 2 is canceled out isometrically, thereby preventing vibration of the tracking actuator 1) 2.

On the other hand, during tracking mode when the 5-source spot follows the center of the track of the original disk 101, the internal signals of the tracking actuator drive control circuit 1) 5 and the linear actuator drive control circuit 1) 7 are transferred to the disk motor drive control circuit 103. It is synchronized with the rotational phase pulse of the original disk 101 sent from the source disk 101 and stored in the waveform storage circuit 12). When accessing a track, this signal is sent to the tracking actuator 1) 2 and the linear actuator 1) 6. The relative eccentricity between the original spot formed by the optical head 104 and the original disk 101 is reduced by applying it through the respective drive control circuits 1) 5 and 1) 7.

[Problem that the invention seeks to solve]

Since the conventional original disk drive device is configured as described above, the original optical head 1 is detected by the speed detector 1) 9.
Since the absolute speed of the optical head 104 is controlled, even if the moving speed of the optical head 104 is controlled to zero when the source spot enters the target track, eccentricity of the disk 101 and vibrations of the tracking actuators 1 and 2 occur. Therefore, the relative speed between the target spot and the track on the source disk 101 does not become zero, making it difficult to count the number of tracks traversed, and making it difficult for the tracking control system to pull in the target track. Therefore, a comparative waveform memory circuit 12) for correcting the eccentric component and a μm CPU interface 122 for controlling it. Or tracking actuator 1) 2
Not only does the configuration of the control system become complicated by the provision of an acceleration detection circuit 120 to prevent vibrations, but also the non-periodic speed of track vibration and the disturbance speed suddenly applied to the original disk 101 can be detected by the speed detector 1). Since it cannot be detected by 9,
During track access, these cannot be suppressed by the linear actuator drive control circuit 1) 7, resulting in problems such as failure of the tracking control system to engage the target track.

This invention was developed to solve the above-mentioned problems, and has a simpler structure that can be used even when track shake, vibration of the tracking actuator, or sudden disturbance speed is applied during track access. It is an object of the present invention to provide a source disk drive device having a track access control system that performs stable speed control of an optical head with respect to the source disk and allows a tracking control system to reliably pull in a target track.

[Means for solving problems]

In the original disk drive device according to the present invention, in order to obtain a speed detection signal that is the speed of the optical head for drive control of the actuator that drives the first optical head during track access, a photoelectric conversion signal of the photodetector of the optical head is transmitted. The periodic response counting means outputs a digital signal having a magnitude corresponding to the period of , and the functional digital-to-analog converting means converts the digital signal into an analog signal based on the magnitude of the digital signal.

[Effect]

The original disk drive device in this invention can obtain a waveform photoelectric conversion signal from the photodetector of the optical head by traversing the track of the optical disk during track access, and the frequency of this waveform signal is the same as the original spot of the optical head. According to the frequency of this waveform signal, a speed detection signal is obtained by the frequency response counting means and the function digital-analog conversion means, so this speed detection signal corresponds to the speed of the original spot relative to the original disk. It corresponds to relative speed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, the symbols 101 to 1)7fl are similar to the above conventional device, and the input side of II'i is the addition/subtraction amplifier circuit 1).
A track crossing number counter is connected to the output side of the sum signal of No. 4 and counts the number of tracks crossed by inputting the sum signal at the time of track access.

The input side of 2 is connected to the output side of the sum signal of the addition/subtraction amplifier circuit 1) 4, and the optical head 104 is connected to the original disk 101.
This is a speed detection circuit that detects the relative speed of the original spot. In addition, tracking actuator drive control circuit 1)
5 has its input side connected to the tracking error signal output side of the addition/subtraction amplifier circuit 1) 4, and its output side is connected to the input side of the tracking actuator 1) 2 and the input side of the linear actuator drive control circuit 1) 7. There is o
It was. The input side of the linear actuator drive control circuit 1) 70 is connected to the output sides of the track crossing number counter 1 and the speed detection circuit 2, respectively.

The other configurations are the same as those of the conventional example, so explanations will be omitted.

FIG. 2 is a more detailed circuit diagram of the speed detection circuit 20 shown in FIG.
1) is a track crossing detection circuit which inputs the sum signal from 4 and outputs a pulse with a frequency corresponding to the speed at which the track is crossed; 1) is a reference clock generator which generates a reference clock;
12 is an input signal period counter whose input side is connected to the output side of the track crossing detection circuit 10 and the reference clock generator 1), and which counts the clock input every time one track pitch is moved; The reciprocal function generator 14 outputs a digital signal as a count value that is inversely proportional to the count value of the reciprocal function generator 13. The reciprocal function generator 14 is a digital-to-analog converter that converts the digital signal of the reciprocal function generator 13 into an analog signal.

FIG. 3 is an explanatory diagram illustrating the operation of the speed detection circuit 2, in which a shows a cross section of the original disk 101, 15 is an unrecorded track groove, 16 is a recorded track groove, and b in the figure is F1.
C in the same figure shows the output of the track crossing detection circuit 10 for the sum signal of b, respectively.

Figure 4 is a diagram showing the output of each part of the speed detection circuit 2 when the source spot approaches the target track during track access.) In Figure 1, a is the output of the sum signal of the addition/subtraction amplifier circuit 1) 4 b is the output of the track crossing detection circuit 10, C is the output of the reference clock generator 1), and d is the output of the digital-to-analog converter 14, that is, the output of the speed detection circuit 2. The track crossing number counter 1 is composed of a circuit having the same configuration as the track crossing detection circuit 10 and a counter for counting output pulses thereof.

Next, the operation will be explained. The original light from the light source 106 is converted into parallel light by the collimator lens 107, converted into linearly polarized light by the polarizing beam splitter 108, passed through the λ/4 plate, reflected by the mirror 1)0, and then reflected by the objective lens. 1)
1, an original spot is formed on the original disk 101 which is constantly rotating.

The original reflected from the original disk 101 is the objective lens 1) 1
The light returns from there to the polarizing beam splitter 108, is reflected by the polarizing beam splitter 108, and enters the splitting photodetector 1)3. The source incident on the split photodetector 1) 3 is photoelectrically converted by the split photodetector 1) 3, and this photoelectric conversion signal is converted into a sum signal and a tracking error signal by the addition/subtraction amplifier circuit 1) 4. . The sum signal is track crossing number counter 1
The tracking error signal is input to the speed detection circuit 2 and the tracking actuator drive control circuit 1) 5.
becomes the input. Here, when performing track access control, the linear actuator drive control circuit 1) 7 controls the optical head 104t-
The original disk 101 is moved in the radial direction.

Here, the original disk 101 has track grooves cut in advance as shown in FIG. 3A.

When the original spot crosses the track, the original disc 101
Due to changes in the amount of reflected light from the recording medium, the sum signal of the outputs of the divided photodetectors 1) and 3 during recording using the punching method has a waveform as shown in b in the figure. That is, when the original spot passes over the recorded bits of the recorded track groove 16, the amount of reflected light decreases significantly, and the level of the sum signal also decreases. Therefore, b in the same figure
When the track crossing detection circuit 10, which uses the level shown by the dashed line as a threshold, compares the sum signal shown in the figure, a track crossing signal shown in C in the figure is obtained. Immediately before reaching the target track during track access control, the optical head 104 is in a deceleration state, and the sum signal of the addition/subtraction amplifier circuit 1)4 becomes as shown in a of FIG. Therefore, the output of the track crossing detection circuit 10 is as shown in FIG. 4b.

On the other hand, the reference clock generator 1) generates a reference clock that constantly oscillates at a constant frequency that is sufficiently higher than the frequency of the track crossing signal as shown in FIG. 4C. The input signal period counter 12 calculates the number of reference clocks of the reference clock generator 1) that are input within one period of the track crossing signal shown in FIG. In addition, the input signal period counter 1
2 is a track crossing signal every 1H rubel hour or 1L
The reference clock may be counted every time the clock reaches 0 level. ).

This count is proportional to the period of the track crossing signal,
There is an inverse relationship with the track crossing speed of the original spot.

Therefore, the reciprocal function generator 13 inputs the output of the input signal period counter 12 every time the track crossing signal rises (or falls), and outputs a count value whose magnitude is opposite to that of the count value of the counter 12. For example, speed information is obtained, and the speed detection signal obtained by converting this speed information into an analog signal by the digital-to-analog converter 14 corresponds to dK in FIG.

This speed detection signal is generated every cycle of the track crossing signal as can be seen from dt in FIG. Also, b in Figure 4
As can be seen from the comparison with dt- in the same figure, the shorter the period of the track crossing signal, the faster the speed of the source spot where the level of the speed detection signal is high.

Returning to Figure 1 again, when accessing the track.

The linear actuator drive control circuit 1) 7 is based on the count value indicating the position of the original spot on the original disk 101 and the speed detection signal detected by the track crossing number counter 1 and the speed detection circuit 2.

Linear actuator 1) 6 or optical head 104
By moving t-, the relative speed of the original spot on the original disc 101 with respect to the original disc 101 is controlled. Immediately after the 1 yuan spot reaches the target track,
The tracking actuator drive control circuit 1) 5 operates, and the addition/subtraction amplifier circuit 1) 4 also controls the tracking actuator 1) 2 based on the output tracking error signal.
At the same time as driving, a tracking control signal is also sent to the linear actuator drive control circuit 1) 7, and the linear actuator 1) 6 is also driven to enter a tracking mode in which the primary spot follows the track center of the original disk 101. In this tracking mode, the linear actuator drive control circuit 1) 7 does not refer to the position and speed information sent from the track crossing number counter 1 and the speed detection circuit 2.

As described above, in the original disk drive device of this invention, the speed detection circuit 2 detects the relative speed between the track of the original disk 101 and the original spot, so the vibration of the tracking actuator 1) and the Even if there is track wobbling due to eccentricity of the original disk 101, the 1 linear actuator 1) 6 is driven so as to cancel this movement, and the relative speed between the track of the original disk 101 and the original spot is controlled. . Therefore, the optical tracking actuator 1) shown in FIG.
2 is no longer necessary, which simplifies the configuration of the control system and leads to cost reductions.

Additionally, this invention is useful for reducing the non-periodic speed of track runout,
Disturbance speeds that are suddenly applied to the source disk 101 are also detected, and the control system of the present invention suppresses them, so that stable track access operations can always be realized.

In this embodiment, the reciprocal function generator 13 is provided before the digital-to-analog converter 14 as shown in FIG. A container may be provided. In this case, the digital signal output from the input signal period counter 12 is converted into an analog signal by a digital-to-analog converter, and an analog signal having the opposite magnitude to this analog signal is outputted by an analog reciprocal function generator. Of course, this is a good thing.

FIG. 5 shows another embodiment of the invention. In this embodiment, the track crossing detection circuit 10 shown in FIG. 2, which is used for the track crossing number counter 1 and the speed detection circuit 2 in the embodiment shown in FIG. 1, is used in common. Therefore,
The speed detection circuit 17 is composed of elements 1) to 14 except for the track crossing detection circuit 10 shown in FIG. Therefore, the input of the speed detection circuit 1T is taken from the output of the track crossing detection circuit (corresponding to 10 in FIG. 2) of the track crossing number counter 1.

In each of the above embodiments, a one-beam system has been described, but it goes without saying that the present invention can be applied to any system that can obtain a sum signal and a tracking error signal.

Note that the control signal may be used to determine whether or not the speed detection circuit and the tracking actuator drive control circuit shown in FIGS. 1 and 5 operate.

〔Effect of the invention〕

As described above, according to the present invention, the speed detection signal obtained by measuring the relative speed between the primary disk and the optical head, that is, the original spot using the speed detection circuit is used for track access control. .

This eliminates the need for an acceleration detection circuit, a waveform storage device, etc., simplifies the configuration of the original disk drive, provides stable track access control, and provides improved reliability.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the original disk drive according to an embodiment of the present invention, Fig. 2 is a block diagram of the speed detection circuit, Fig. 3 is an explanatory diagram of the operating principle of the speed detection circuit, and Fig. 4 is the speed detection circuit. FIG. 5 is a diagram illustrating the operating principle of the circuit, FIG. 5 is a block diagram of an original disk drive device according to another embodiment of the present invention, and FIG. 6 is a diagram showing the configuration of a conventional disk drive device. In the figure, 1 is a track crossing number counter, 2 is a speed detection circuit, and 10 is a track crossing detection circuit. 1) is a reference clock generator, 12 is an input signal period counter, 13 is a reciprocal function generator, 14 is a digital-to-analog converter, 101 is an original disk, 104 is an optical head, 1)
4 is an addition/subtraction amplifier circuit, 1) 5 is a tracking actuator drive control circuit, 1) 6 is a linear actuator, 1
) 7 is a linear actuator drive control circuit. In each figure, the same reference numerals indicate the same or similar parts. Patent Applicant: Mitsubishi Electric Co., Ltd. Cup 3 = E2 Figure 3 @ 4! H -d -ノ″″′-″ Danro
- Procedural amendment (voluntary)

Claims (2)

[Claims] (1) An optical head is provided with a photodetector that forms a light spot on an optical disc having a large number of track grooves and receives reflected light from the optical disc, and when accessing a track of the optical disc, the optical head In an optical disk drive device that detects a moving speed and controls an actuator that moves the optical head in a radial direction of the optical disk based on the detected speed detection signal, a photoelectric conversion signal photoelectrically converted by the photodetector is input. , period response counting means for outputting a digital signal of a magnitude corresponding to the period of the photoelectric conversion signal, and inputting the digital signal and outputting an analog signal as the speed detection signal based on the magnitude of the digital signal. What is claimed is: 1. An optical disk drive device comprising function digital-to-analog conversion means. (2) The optical disk drive device according to claim 1, wherein the photodetector is a split-type photodetector, and the photoelectric conversion signal is a sum signal of the split-type photodetectors.